<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>promise_ajax</title>
    <link rel="stylesheet" href="./index.css">
</head>
<body>
    <h1>promise_ajax</h1>
    <button class="btn">点击发送请求</button>
    <script src="index.js"></script>
</body>
</html>